Tens of thousands of naked Hindu ascetics and millions of pilgrims took dips in freezing water at the confluence of sacred rivers in northern India on Tuesday, in the first of a series of major baths in the Maha Kumbh festival,

Vast crowds of Hindu pilgrims in India readied on Monday to bathe in sacred waters for the Kumbh Mela festival, with organisers expecting 400 million people -- the largest gathering of humanity.India is the world's most populous nation,

With over 400 million expected to attend, the Maha Kumbh Festival is the largest religious gathering on Earth.

Scores of naked Hindu ascetics smeared in holy ash charged into the water of holy rivers in northern India on Tuesday, dreadlocks flying, during the first 'royal bath' of the Maha Kumbh Mela, or Great Pitcher Festival.

Over about the next six weeks, Hindu pilgrims will gather at the confluence of three sacred rivers where they will take part in elaborate rituals.